Percentage-calculator



(No Model.)

S. J. TUCKER 85 E. F. KELLY. PERCENTAGE CALCULATOR.

o. 280,772. Patented July 3, 1883.

WITNESSES 0/ A INV ENTOR W W Jab/ 1% ATTORNEYS.

UNITED STATES PATENT OFFICE.

SYLVESTER J. TUCKER AND EDMUND F. KELLY, OF RICHMOND, VIRGINIA.

PERCENTAGE-CALCULATO R.

SPECIFICATION forming part of Letters Patent No. 28G,'7'72, dated July 3, 1883.

Application filed December 2,1882. (No model.)

-, rates, revenues, or expenses on the basis of mileage; and we hereby declare that the following is a full, clear, and exact description of. the same, reference being had to the annexed drawings, forming part of this specification.

The invention consists of a graduated base having several series of numerals arranged thereon in horizontal, transverse, and quad- I rantal orders, respectively, and in such relation to each other that an arm pivoted to the base shall be adapted to indicate the percent age a given number bears to a greater number.

The drawing represents a plan view of our invention, in which Aindicates the graduated base, having a series of numerals, B, the denomination of which increases from left to right along the upper margin of the base, a series of numerals, 0, increasing in denomination downward or from the aforenamed margin, and a third series of numerals, D, arranged in ascending order from the left-hand side of the base tothe said upper margin in the form of a quadrant. Corresponding to the series of numerals, respectively, are horizontal lines E, transverse lines F, and quadrantal lines G, and radial lines H. The series of numerals B may be repeated, for the sake of convenience, on any or all of the horizontal lines E. It is more necessary to convenience, however, that the series of numerals 0 should be repeated at intervals across the base. The series of numerals D are placed on the radial lines H. Now, the several series of numerals are so arranged with respect to each other that when the arm I, which is pivoted at the center, of the circle of which the quadrant forms apart, is .madeto indicate anumber on the quadrant say 1,000the percentage of a fractional part of one thousand-say two hundred and fiftywill be indicated by the number 25, which appears at the intersection of the arm I withthe transverse line, on which 250 is placed. In the same manner the percentage of any other fractional part of one thousand may be ascertained at a glance; or the percentage of a fractional part of any other number may be indicated by the proper adjustment of the arm.

Instead of the transverse lines F and series of numerals O, a T-square having such a series of numerals may be used in connection with the arm I to indicate the percentage.

Having thus described our invention, what we claim as new, and desire to secure by Letters Patent, is-

A percentage calculator consisting of a graduated base having several series of numerals arranged thereon in horizontal, transverse, and quadrantal orders, respectively, which bear such relation to each other that an arm pivoted to the base shall be adapted to indicate a number in each of the series, of which one shall represent a sum total, another a fractional part thereof, and the third the percentage the part bears to the whole, substantially as shown and described, and for the purpose set forth.

SYLVESTER J. TUCKER. EDMUND F. KELLY.

WVitnesses: G. O. BRIDGES,

W. M. CAMPBELL. 

